1. Technical Field
The present invention relates to a connecting device, a connecting system, an optical waveguide and a connecting method. More particularly, the present invention relates to a connecting device, a connecting system, an optical waveguide and a connecting method for connecting electrical circuit substrates to each other in such a manner that signal transfer is possible between the electrical circuit substrates.
2. Related Art
A technique has been proposed to signal-connect together two electrical circuit substrates which are parallel to each other based on optical space transmission. For example, refer to Japanese Patent Application Publication No. 09-44272 and T. Szymanski and H. S. Hintor, “Architecture of a Terabit Free-space photonic backplane”, The international conference on optical computing technical digest, October 1994. According to the proposed optical space transmission technique, the signal is transferred without going through any backplanes. Therefore, the two electrical circuit substrates can be efficiently connected to each other.
However, the above-mentioned technique has problems. In order that optical transmission is realized between the two substrates, the substrates need to be highly accurately positioned to prevent misalignment between a light emitting section and a light receiving section. Furthermore, when a large number of optical transfer paths are created, light leakage may cause interference, which may degrade the communication quality. Additionally, when optical transmission is realized between the two substrates, the light emitting section and the light receiving section remain externally exposed. Therefore, dirt and dust may attach to the light emitting section and the light receiving section, and the communication quality may accordingly deteriorate.